Despite the availability of blood products, blood loss is a major cause of morbidity and mortality. There are many causes of such loss, including severe injury and clinical conditions such as the rupture of an aneurysm, esophageal or gastric ulcers, and esophageal varices. A loss of integrity of a major artery can rapidly lead to death, particularly if it occurs in a setting where there is no rapid access to medical care.
Bleeding during surgery is often a major concern. Blood loss can cause a myriad of problems for the patient while the presence of blood in undesirable locations can be detrimental to normal tissue or interfere with the surgeon's ability to view the operative field. The surgery must be delayed while blood is removed and the bleeding is brought under control. Bleeding can be problematic even during minimally invasive surgery (e.g., laparoscopic surgery). In some instances, surgeons must convert these preferred procedures into traditional open surgeries if bleeding cannot be adequately controlled.
Bleeding can also be problematic in diagnostic and interventional procedures that involve the percutaneous introduction of instrumentation into an artery, vein or smaller vessel. For example, procedures such as coronaryangioplasty, angiography, atherectomy, and stenting of arteries often involve accessing the vasculature through a catheter placed into a blood vessel such as the femoral artery. Once the procedure is completed and the catheter or other instrument is removed, bleeding from the punctured vessel must be controlled.
Options for controlling bleeding in any of these settings are limited. One of the oldest methods includes application of pressure, either directly to a vessel or to the body external to the vessel. Pressure must be maintained until the bleeding is under control. This procedure is time-consuming and inconvenient, and the patient is at risk of hematoma. Other physical methods include the use of clamps, clips, plugs, sponges, or the like. These devices have limited efficacy, and they can be cumbersome to apply, particularly if there are many small bleeding vessels. Use of heat to coagulate blood and cauterize bleeding vessels is widely used during surgery, but it is a destructive process that can result in damage to collateral tissue. Furthermore, these methods require equipment and expertise and are thus not suitable for use outside of medical settings. In addition to heat and mechanical devices, a variety of compounds have been used to promote hemostasis, but none of these are ideal.
Accordingly, improved methods are needed.